Chelsea boss Jose Mourinho was sent to the stands after the skirmish, which occurred when Chelsea's Ramires was sent off for a wild tackle on Karim El Ahmadi in injury-time.
The incident occurred right in front of the dug-outs and Mourinho, Villa boss Paul Lambert, and several coaches from both sides came onto the pitch to try and defuse the situation.
Having been ushered away initially, Mourinho returned to engage in further dialogue with Foy and was sent to the stands by the referee.
The Chelsea boss claims he wanted to speak about the fact that Villa's Gabriel Agbonlahor escaped punishment for charging off the bench and grabbing Ramires.
However, he may still face an FA charge because their rule book says managers must not leave the confines of their technical area during the match.
Rule E3 states any manager who does so could be liable to an FA charge, with a fine of £8,000-£12,000 a possible punishment.
And, if it is ruled that Mourinho, or any of the staff members from either side, used abusive language, they could be hit with a two-match suspension.
Mourinho will find out if his conduct is to be investigated after the FA has received Foy's report on Monday.
And Agbonlahor may also be sanctioned for the role he played in the melee.